Weight and tension measuring device



- NbvQ-24, 1936.

W. T. WELLS WEIGHT AND TENSION MEASURING DEVICE File d Oct. 21, 19:55

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2 Sheets-Sheet 1 INVENTOR Nov. 24, 1936. 7 w. T. WELLS WEIGHT AND TENSION MEASURING DEVICE Filed 0ct. 21, 1955 2 Sheets Sheet 2 1N VENTOR 30 rick equipment, must of necessity be very rugged drum 26 of draw-works. The wire line is now 30 springs meshed together, the number of springs medium used and the diameter of same, and may 55 Patented Nov. 24, 1936 I I 2,061,863

UNITED STATES PATENT OFFICE 2,061,863 WEIGHT AND TENSION MEASURING DEVICE Walter T. Wells, Glendale, Calif., assignor to The Technicraft Engineering Corporation, Los Angeles, Calif.-, a corporation of California Application October 21, 1933, Serial No. 694,564 12 Claims. (01. 177- -351) This invention relates tothe means and methbeing the same as the number of strands, and the d ofv measuring the tension in a wire-line or pitch of coils equalling the lay of the cable. the amount of weight suspended from it. It has Stranded wire rope is fabricated around a hemp proved to be of great utility in and around oil core, which core is of no particular value after wells, where great quantities of cable or strandedthe line is made. The hemp core does serve a 5 wire line are used, and is extremely simple and useful purpose during manufacture and is used at the same time most accurate in results. to prevent the strands from being compressed Many devices have been conceived for measurunevenly. I elect to leave out a part of this core ing the tension in a line, but all are more or less and use other materials in its place that will complicated and not adapted 'for conditions in answer the same purpose as far as manufacture, 10

a the petroleum industry on drilling rigs, where it and yet serve a useful purpose during the lifeof is necessary to keep both ends of the line free the line. Further features of this invention will for wrapping on a hoisting drum, so devices that appear as the description progresses. clamp on the outside of. the cable must be re- Referring to Figure l, the usual derrick is moved before the cable is operative. Such r'eshown at I, upon which is mounted a crown block 15 moval consumes some time which is often of great 2, with sheaves 3 and from'which is hung trav-. value, and when such devices are replaced on the elling block 4, clevis 6, clevis 1, pin 8, through cable, the calibration is changed. Many devices which is passed hook 9.he1d in Place by c a have been conceived to'be placed in the hook or From the hook 9 allmanner of clevices'are hung,

swivel, but these of necessity require a flexible but I show links [2 attached to elevator I3, 20 connection to enable the hook to be raised and clamped around P p l4 under the Collar one lowered in the derrick, and still keep the device d of the wi lin 3 is placed'around the drum operative. Furthermore when weight-indicating 22 0f calf-Wheel through the flange l9 in devices are considered for operation onthe hook hole 2| and clamped on by clamp I1 and cap 5 or swivel, they must be strong enough to withscrews I8. Some four or five hundred feet of line 25 stand the total pull, which may be up to 250 tons. is th n w apped on th drum. t other nd th A mobile device for these conditions on the hook, .carried up over he r wn block Sheaves, threadsensitive enough to read the weight from any ed back and forth through the traveling block small amount up to the capacity of the usual dersheaves and pulled down and attached to the and heavy. The limitations for a sensitive device operative between two hoists and hook-'9 may be for this purpose are very great.- raised and lowered by means of engines rotating In my invention I use space that is entirely the drums ofthe hoists. The usual method of wasted, do not interfere with any of. the well stringin up a wire line p ds on he w i ht equipment, and the device can be used in any to be handled, and the number of lines may be 35 place Where a wire line canbe used. The object six; eight, or ten. The wire line used in my inof my invention is therefore to provide a simvention is made in the usual stranding and preple tasuring device for a line, to deterforming machines, but in the first six hundred mine the amount of weight suspended from the feet from end 23, instead of the hemp core I use line or the amount of tension in the line, that an insulated electrical conductor for a core. The 40 is accurate and inexpensive and not affected by construction of. this wire line is shown complete outside conditions.- ly in my co-pending application 662,901, filed In the accompanying drawings, Figure 1 shows March 2'7, 1933, and is used in this line up to a in elevation the general arrangement of an oil point shown at BB in Figures 1 and 3. At this well cable, but partly in section at the hoists. point the construction of the core is changed and 45 Figure'2 shows the part of my device that is a rubber tube 26 is used, with a small hole 21 in attached to the shaft of the emergency hoist to the center. The end of the rubber tube is slipped which one end of the wire line is attached. over contact 28, which is in turn soldered to the Figure 3 shows partly in section the activating end of conductor 3| and vulcanized and molded.

part of. my device which. would normally come around the conductor 29 and contact 28 to'make 50 between A and B in Figure 1. a fluid-tight seal, as well as an insulated joint, Figure 4 is an electrical diagram showing the where it joins the rubber 32 of the conductor. connections. The length of the rubber tube 26 varies withthe In effect a stranded wire line is a series of coil amount of resistance desired and the resistance vary from a few inches to a hundred feet. The hole 21 is then filled with mercury 39 or other high-resistance material that is'capable of elongation. Contact 36 is then placed in the tube in contact with the mercury 39 and soldered to cup contact 38 at 31, and the rubber vulcanized to the contacts so that the mercury is entirely sealed.

within the rubber. From the point 31 for the remainder ot'the cable above AA over the crown block. and travelling block down to the drawworks drum, the regular hemp core 4| of the cable is used. The rubber core is covered with a fabric braid 33 impregnated and coated with a scribed in my co-pending application No; 662,901,

filed March 2'7, 1933. It is thus seen that I have provided an extensible resistance unit, thoroughresistance elongate.

1y protected in the center of the wire line, and when any strain is placed on the wire line it elongates. This may amount to 15% elongation within the safe limit of the line. As the wire line elongates in proportion to the stress in the line or weight applied to it, so must the extensible As the mercury elongates, its resistance increases in proportion to the e1ongation, and also increases due to the decrease in diameter. The electrical circuit within the cable is then through conductor 3|, which must be very low in resistance as compared with the resistance of the mercury, through the contact 28, through the mercury 39, through contact 36, soldered at- 31 into cup contact 38, whichis in contact with the steel strands, and back through the steel strands 42. By providing a source of direct currentof known potential at 43, connected in series through ammeter 46 to the conductor 3|, through slip ring 41, and connecting the other direct currentpole oi. the source to the steel strands through collector ring 44, the resistance may be measured. By keeping the potential constant as shown on voltmeter 49, alloi? the resistance in the circuit except the mercury column remains constant, so asthe resistance 01' the mercury column changes due to elongation, so the current as shown by ammeter 46' will change in direct pro- 36 connected to the battery or direct current source, while the insulated end of conductor 3| is,

brought through bore 54 in the shaft at 53.

Brush 65 contacts the slip ring 41 and is in turn a cable comprising: an insulated conducting.

connected to the source of. energy 43 through the ammeter 46. The cable will be built so that in operation the resistance unit will come approximately between AA and BB, although the stress 'middle and be made operative by thuse c1 onej collector ring on the shaft of each hoist, but this would be more expensive to manufacture.

. While I have shown the preferred embodiment of my invention as applied to adrilling cable in an oil well, there are many other applications for this device. For example, a dynamometer for measuring-the tension in high-voltage power lines may be made by using a piece of. stranded line containing an extensible resistance unit between the dead end and a pulling clamp, and very accurate readings taken. Once my device is calibrated, it is very accurate and not subject to much variation due to temperature changes nor changes in friction. With the mercury column of very small diameter, it is possible to weigh very small increases in weight on a l-inch or.1%-inch drilling line, after the initial stretch is-removed. Furthermore, should excessive strains be applied, and a permanent stretch be placed in the line; it is only necessary to set to a new zero on the dial and recalibrate the scale. There are many other materials and compounds made up in liquids, pastes, or semi-solids, of high resistance, that can be used in place of mercury, depending upon conditions of use and compound of rubber or flexible dielectric used. This device may be made up in a short piece of stranded cable and placed between the bail 6 and clevis I, but would, require a connection so designed as to permit the raising :and loweringjof the travelling block.

I claim:-

and variable resistance element within a chamber defined by said cable, and responsive to lineal variations of said cable; a conductor within said cable connected with said resistance element, and means for measuring variations in the resistance of said element.

2. In combination; multiple stranded weight supporting rope; a variable resistance means within said rope, said resistance means comprising a resilient envelope of insulating material and-a relatively conductive fluid material therein; and means connecting said fluid material to a source of electrical energy.

3. In a multiple stranded weight supporting cable, an insulated conductor therein, an insulated fluid column resistance element within said stranded cable contractible and extensible therewith and electrically connected with said insulated conductor.

4. In a weight and tension measuring device; a

multiple stranded weight supporting" rope; an

insulated variable resistance element disposed within a chamber in the rope, which chamber and contained resistance are subjected to lineal strains and responsive to elongation and contraction or the rope; a conductor means leading from said resistance element; and means connected with said conductor means for measuring variations in the resistance element in response to elongation and contraction of the rope.

5. In a. weight and tension measuring device;

core occupying at least a portion of said cable, and a variable resistance element continuing from said core within a chamber providing a arrangement .including said conducting core, resistance element, cable and measuring means.

6. The combination with a resistance measurresistance value which ing means; of a weight and tension determining cable comprising; a core; a multiple stranded weight supporting lay; an insulated elongated variable resistance element forming a portion of said core and varied in dimensions by elongation and contraction of the portion of the weightsupporting lay therearound; and conductor means leading from said resistance element to said measuring means.

7. The combination with a resistance measuring means; of a weight and tension determining cable comprising: a core; a multiple stranded weight supporting lay; an insulated elongated variable resistance element forming a portion of said core and varied in dimensions by elongation and contraction of the portion of the weight supporting lay therearound; and a conductor means incorporating a portion of said core and a portion of said weight supporting lay I and leading from said resistance element to said measuring means.

8. A weight or tension indicator comprising: a readily deformable element whose resistance is a function of its length; a yieldable weight supporting means surrounding said resistance element and providing a non-conducting wall therefor and connected with a load to elongate and contract in response to variations of said load and correspondingly influence said resistance element; and electrical means for measuring the resistance of said resistance element.

9. A weight or tension indicator comprising: an insulated variable resistance element having a varies upon elongation and contraction; a yieldable weight supporting means surrounding said resistance element and connected with a load to elongate and contract in response to variations of said load and correspondingly influence said resistance element; conductors leading from said resistance element; a source of electrical energy to pass current through said resistance element; and measuring means arranged in a circuit with said resistance element to indicate variations in its resistance.

10. In a cable for weight and tension. measuring purposes; the combination with a weight supporting lay capable of elongation and contraction, of a core comprising in part, a readily deformable insulated elongated variable resistance element within said weight supporting lay and partaking of the elongation and contraction thereof.

11. In a cable for weight and tension measuring purposes; the combination with a weight supporting lay capable of elongation and con, traction; of a core comprising in part only of an insulated elongated variable resistance within said weight supporting lay and partaking of the elongation and contraction thereof, and an insulated conductor means leading from said resistance to an end of said cable.

12. A load sustaining cable formed with a hollow section having a non-conducting wall, said hollow section having a longitudinal dimension varying directly and a transverse section varying inversely with cable loads, a yieldable body filling said hollow section, said body having instantaneous resistance values proportional to its dimensions, and means for measuring said values.

WALTER 'nwELLs. 

